function dXdt = capacitive(t, X, param)
% 阻抗耦合
% 状态向量 X = [V1; iL1; V2; iL2]

    x1 = X(1);
    y1 = X(2);
    x2 = X(3);
    y2 = X(4);
    z  = X(5);

    b = param.b;
    r = param.r;
    c = param.c;
    n = param.n;
    lambda_C = param.lambda_C;
    
    % 混沌电流和外部声信号
    I_Chaos = param.iChaosFunc(t);
    u_PC = param.vPCFunc(t);

    % 电容耦合的计算
    dx1 = x1 - (1/3) * x1^3 - y1 + I_Chaos + lambda_C * (x2 * (1 - eta) - (1/3) * x2^3 - y2 + n * u_PC - (x1 - (1/3) * x1^3 - y1 + I_Chaos));
    dy1 = c * (x1 + b - r * y1);
    dx2 = x2 * (1 - n) - (1/3) * x2^3 - y2 + n * u_PC - lambda_C * (x2 * (1 - eta) - (1/3) * x2^3 - y2 + n * u_PC - (x1 - (1/3) * x1^3 - y1 + I_Chaos));
    dy2 = c * (x2 + b - r * y2);

    dXdt = [dx1; dy1; dx2; dy2];
end